In the past, it has been found desirable to use amperometric analysis of biosensing cell assemblies. Such analysis was possibly subject to electromagnetic interference because of the loop formed by such cells in their disposable form, wherein a pair of conductors were supported on an insulating substrate with a remote test cell completing the circuit for analysis of a response current, which in one embodiment may be a Cottrell current. In the prior art, any stray electromagnetic fields present to the biosensing cell assembly may cause a spurious signal (“noise”), interfering with and distorting the response current. The present invention overcomes this difficulty by providing a noise cancellation apparatus and method to improve the measurement of the response current in such biosensing cell assemblies.